1. Field of the Invention
The present invention relates to a cryosurgical probe and in particular to a cryosurgical catheter probe for percutaneous employment in a surgical procedure.
2. Description of the Prior Art
Cryosurgical probes are presently in use for freezing body tissue to a degree sufficient to produce a temporary reversible block of electrical conduction through tissue, an inflammatory response, cryo-adhesion or cryo-necrosis. The probe tip is cooled by passing refrigerant (liquid, gas or vapor) at high pressure through a restriction at the tip to cause a loss of pressure with consequent loss of heat and rapid cooling. This phenomenon is commonly known as the Joule-Thomson effect, and is used significantly to reduce the temperature on the exterior surface of the probe tip which is then used for the freezing process.
Such probes are extensively used to freeze external body tissue, and surgically exposed tissue for example in the treatment of skin cancer. However an extension of the use of cryogenic probes for the treatment of internal organs, such as the heart, is now under further active consideration.
In the application of a cryogenic probe to treat the human heart, for example to freeze and destroy aberrant conductive heart tissue, it is necessary to maneuver the probe along the femoral artery from a position in the groin to direct the tip at the end of the probe to the area to be treated.
To achieve this purpose the probe has to be given a steerable capability to enable the surgeon readily to manipulate the probe along the artery to its final destination which necessarily involves a certain amount of twisting or torque being applied over a constantly increasing distance as between the chosen entry to the artery and the probe tip.